The present invention relates to methods for treating the prostate and/or prostatic urethral stents configured for use after thermal ablation treatments.
Conventionally, several types of thermal treatment systems have been proposed to treat certain pathologic conditions of the body by heating or thermally ablating targeted tissue. These thermal treatment systems have used various heating sources to generate the heat necessary to treat or ablate the targeted tissue. For example, laser, microwave, ultrasound, and radio-frequency (RF) energy sources have been proposed to produce the heat that is then directed to the targeted tissue in or around the selected body cavity. These types of thermal treatment systems have been used to thermally ablate the prostate (as well as other organs, body cavities, and/or natural lumens).
One particularly successful thermal ablation system thermally ablates the prostate by a thermocoagulation process. This thermal ablation system employs a closed loop liquid or water-induced thermotherapy (WIT) system which heats liquid, typically water, external to the body and then directs the circulating heated water into a treatment catheter which is inserted through the penile meatus and held in position in the subject undergoing treatment to expose localized tissue to ablation temperatures. The treatment catheter includes an upper end portion which, in operation, is anchored against the bladder neck and an inflatable treatment segment which is held relative to the anchored upper end portion such that it resides along the desired treatment region of the prostate. In operation, the treatment segment expands, in response to the captured circulating fluid traveling therethrough, to press against the localized or targeted tissue in the prostate to expose the tissue to increased temperatures associated with the circulating liquid, thereby thermally ablating the tissue at the treatment site. In addition, the pressurized contact can reduce the heat sink effect attributed to blood circulation in the body, thus enhancing the depth penetration of the heat introduced by the inflatable treatment segment into the prostatic tissue.
As an acceptable alternative to surgery (transurethral resection of the prostate (TURP)), the use of WIT has been shown to be particularly suitable for the treatment of BPH (benign prostatic hyperplasia). Generally stated, the term xe2x80x9cBPHxe2x80x9d refers to a condition wherein the prostate gland enlarges and the prostatic tissue increases in density which can, unfortunately, tend to close off the urinary drainage path. This condition typically occurs in men as they age due to the physiological changes of the prostatic tissue (and bladder muscles) over time. To enlarge the opening in the prostatic urethra (without requiring surgical incision and removal of tissue), the circulating hot water is directed through the treatment catheter, which is inserted into the penile meatus up through the penile urethra and into the prostate as described above. The treatment segment expands with the hot water held therein to press the inflated treatment segment against the prostate, which then conductively heats and thermally ablates the prostatic tissue. The circulating water is typically heated to a temperature of about 60-62xc2x0 C. and the targeted tissue is thermally treated for a period of about 45 minutes to locally kill the tissue proximate the urinary drainage passage in the prostate and thereby enlarge the urinary passage through the prostate.
Subsequent to the delivery of the thermal ablation treatment, the treated tissue in the prostate undergoes a healing process. Initially, the ablated tissue can expand or swell due to inflammation or edema which can undesirably block or obstruct the prostatic urethra. Further, during the healing period, portions of the treated tissue can slough off and create an undesirable and unduly limited opening size. Thus, to facilitate proper healing and to enhance the efficacy of the ablation therapy, either the treatment catheter is left in the subject for a period of time and/or the treatment catheter is removed and a post-treatment catheter, such as a conventional Foley catheter, is reinserted and positioned in the subject. However, removal of the treatment catheter and reinsertion of another catheter or stent may cause the tissue along the insertion path and/or treatment region to experience additional irritation. In addition, the amount of time that the treatment or post-treatment catheter must reside in the subject can be from 2-14 days, or even longer. Therefore, it is desirable to configure the post-treatment stent in a minimally invasive manner to allow normal operation of the sphincter, remove the need for the use of an incontinence bag, and reduce the inconvenience or discomfort to the user.
Conventionally, Foley-type catheters with bladder anchoring balloons located on an upper end portion have been used as post-treatment catheters to allow the thermally ablated tissue to mold around the catheter perimeter during the initial healing phase. While these type catheters allow the post-treatment catheter to be securely positioned relative to the bladder neck of the subject, natural operation of the sphincter is inhibited, and the configuration is relatively cumbersome (in position it extends through the penile urethra) and can be considered unduly invasive by the user and may increase the risk of urinary tract infection (UTI) when in position in the subject (particularly, when used for extended periods of time). Other post-treatment catheter configurations (also known as xe2x80x9cindwelling cathetersxe2x80x9d and xe2x80x9cstentsxe2x80x9d) have also been proposed; however, some of the catheter types can inhibit the ability to flush out blood clots which may exist from the therapy, and others are undesirably invasive to the user and/or prevent or inhibit the natural operation of the sphincter. Still others are not able to be properly located within the prostatic cavity about the treatment region and/or are unable to retain their desired position in the prostate over time. Still others can, during prolonged use, promote muscle atrophy and/or localized tissue necrosis.
Examples of known post-treatment catheters or stents are described in U.S. Pat. No. 5,916,195 to Eshel et al., U.S. Pat. Nos. 5,876,417 and 5,766,209 to Devonec et al., and U.S. Pat. No. 3,811,450 to Lord. However, there remains a need to provide improved and/or minimally invasive stents and/or post-treatment catheters or stents that are cost effective and can be positioned in the body, such as in the prostate, proximate the treated tissue, to inhibit the restriction of the cavity or natural lumen. There remains a particular need to provide a prostatic stent that is suitable for use during a post thermal therapeutic treatment (such as ablation) healing process or cycle that can inhibit the closure of the urethra in a manner that reduces abrasion, trauma, or irritation that may be introduced to sensitive tissue along the urethra over conventional treatment procedures.
It is therefore an object of the present invention to provide a biodegradable and/or biocompatible prostatic stent that that can be formed in situ via use of the treatment catheter and is suitable for inhibiting post thermal ablation therapy obstruction in the prostate.
It is another object of the present invention to provide methods to inhibit obstruction in an intermittent or periodic flow passage of natural cavities or lumens in the body to keep the flow passage sufficiently open such that the subject is able to discharge or intake fluids in a substantially normal manner.
It is another object of the present invention to deliver flowable stent material into the patient via the treatment catheter and then to form the stent to conform and be in intimate contact with the walls of the prostatic urethra in situ so as to inhibit obstruction in a lumen or cavity during a healing cycle.
These and other objects are satisfied by the present invention that provides, inter alia, methods for treating the prostate and concurrently forming biocompatible and/or biodegradable stents in the urethra during the same treatment session. In particular embodiments, the stent can be delivered and formed in the prostatic urethra so that it resides above the sphincter, and below the bladder neck, and more particularly, substantially between the bladder neck and the verumontanum. Similarly, the present invention includes methods of treating BPH (and other prostate conditions) in a manner that inhibits obstruction in the prostatic urethra during a healing period after a thermal ablation treatment therapy.
Certain embodiments of the present invention are directed to methods of treating a condition of the prostate and forming a prostatic stent in situ in the prostatic urethra. The method includes: (a) introducing a catheter having an expandable treatment balloon thereon into the male urethra of the subject so that the treatment balloon resides proximate the prostatic urethra; (b) administering a thermal ablation therapy to the prostatic urethra of the subject via the treatment catheter, wherein the thermal ablation therapy has a duration of at least about 10 minutes; (c) releasing biocompatible biodegradeable fluent stent material from the catheter; (d) pressing the fluent stent material into intimate contact with the interior surface of the prostatic urethra by using the expandable treatment balloon; (e) activating the biocompatible stent material in situ to cause it to attach and conform to the interior surface of the prostatic urethra so as to take on a non-fluent form to define a stent having sufficient strength and/or thickness to inhibit closure of the prostatic urethra after administration of the thermal therapy; and (f) then removing the treatment catheter leaving the stent in position in the prostatic urethra.
In other embodiments, the pressing step is optional.
Other embodiments are directed to methods of treating BPH. The methods include: (a) thermally ablating localized tissue in the prostate with a treatment catheter having an expandable treatment balloon thereon; (b) flowing fluent viscous or semi-viscous biocompatible and biodegradeable stent material from the treatment catheter into the prostate; (c) molding the flowable stent material to contact the interior surface of the prostatic urethra by expanding the treatment balloon to press the stent material away from the treatment balloon toward the interior surface of the prostatic urethra; (d) securing the stent material to the prostatic urethra so that it defines a resilient conformable stent that remains in position after removal of the treatment catheter to inhibit the closure of the urinary passage; and (e) removing the treatment catheter from the body of the subject.
Other embodiments of the present invention are directed to catheters for treating a condition of the prostate. The catheter includes: (a) an elongated axially extending shaft; (b) a treatment balloon secured to the shaft and configured to expand outwardly therefrom, the treatment balloon configured to apply a thermal therapy to targeted tissue in the body; (c) a bladder anchoring balloon secured to the shaft above the treatment balloon and configured to expand outwardly from the shaft (that can, in certain embodiments, also substantially securely contact the tissue to define a seal about the upper region above the treatment balloon); (d) a sealing balloon secured to the shaft below the treatment balloon and configured to expand outwardly from the shaft; (e) a urinary drainage channel extending through the shaft; and (f) a flowable biocompatible and biodegradable stent material channel having at least one ejection port formed in the shaft associated therewith, the flowable material channel being in fluid isolation with the drainage channel. The shaft is configured and sized such that the portion intermediate the treatment balloon and anchoring balloon has a decreased cross-sectional width relative to the portion of the shaft intermediate the treatment balloon and sealing balloon thereby allowing easy extraction of the catheter after the stent is formed. In operation, the sealing balloon and the bladder-anchoring balloon are in an expanded configuration when flowable biodegradable stent material is directed to exit the ejection port.
In particular embodiments, the catheter can include at least one flushing port and associated flushing channel disposed in the shaft above the at least one dispersing and/or ejection port. In operation, the flushing port is configured to receive flowable stent material therein and direct it to flow out of the body of the subject in the flushing channel to thereby allow a clinician to verify that the flowable stent material has traveled about the prostatic urethra. A sufficient quantity of flowable stent material can be introduced so as to substantially fill the cavity between the treatment balloon and the walls of the prostatic urethra. In addition, the flushing port may be configured to have a reduced size relative to the ejection/dispersing port to facilitate proper filling of the cavity.
Other embodiments include catheters for treating a condition of the prostate that include (a) an elongated axially extending shaft; (b) a treatment balloon secured to the shaft and configured to expand outwardly therefrom; (c) a bladder anchoring balloon secured to the shaft above the treatment balloon and configured to expand outwardly from the shaft; (d) a urinary drainage channel extending through the shaft; and (f) a non-fluent transformable biodegradeable and biocompatible stent material layer formed over the outer surface of the treatment balloon, whereby when exposed to predetermined temperatures, the stent material is configured to become fluent and released from the treatment balloon to flow to surrounding regions in the prostatic urethra and then, upon exposure to different predetermined temperatures, is configured to become non-fluent and remain in intimate contact with the interior surface of the prostatic urethra to define biocompatible biodegradable stent.
In particular embodiments, the shaft is configured and sized such that the portion intermediate the treatment balloon and anchoring balloon has a decreased cross-sectional width relative to the portion of the shaft immediately below the treatment balloon to allow for ease of extraction of the catheter after the stent is formed in situ.
Other catheters include: (a) an elongated axially extending shaft; (b) a treatment balloon secured to the shaft and configured to expand outwardly therefrom; (c) an outwardly expandable permeable or porous sleeve configured to overlie the treatment balloon, the sleeve being independently inflatable from the treatment balloon; (d) a quantity of flowable biocompatible biodegradable stent material disposed intermediate the treatment balloon and the sleeve; (e) a bladder anchoring balloon secured to the shaft above the treatment balloon and configured to expand outwardly from the shaft; (f) a sealing balloon secured to the shaft below the treatment balloon and configured to expand outwardly from the shaft; (f) a urinary drainage channel extending through the shaft; and (g) a flowable fluent biocompatible stent material channel having at least one ejection port formed in the shaft in fluid communication with the sleeve so as to direct the flowable biocompatible stent material therein, the flowable material channel being in fluid isolation with the drainage channel. In operation, the treatment balloon is adapted to inflate to press the flowable stent material released from the sleeve into the targeted tissue in the body.
Still other embodiments are directed to biodegradable stents for the prostatic urethra. The stent is defined by a non-fluent biodegradable biocompatible polymeric material that is in intimate contact with tissue on the surface of the prostatic urethra and extends a distance into a plurality of the acini (prostate ducts), the biodegradable stent having sufficient thickness and length to inhibit closure of the urinary flow passage through the prostatic urethra. The stent may be employed post-treatment (to attach to ablated tissue) or for hyperplasia or other prostate or urinary tract conditions.
Another aspect of the present invention is a set of prostatic treatment catheters, each configured for insertion into the male urethra of a subject as stated above. However, the set is provided such that each is sized a different length to allow customized fit to a particular subject (the portion of the stent body which is adapted to reside in the prostatic urethra itself).
Advantageously, the present invention provides catheters, methods, and/or post-treatment biocompatible stents that can be delivered via the treatment catheter (before, during, or after active administration of the treatment) in a treatment session so as to inhibit prostate obstruction in the urinary drainage path during post-treatment healing. The stents can be made to be biodegradable (that includes bioabsorbable and the like) and configured to reside in the subject above the sphincter during the healing cycle. As the ablated tissue is sloughed off the surface, the stent will be absorbed or discharged from the body. In certain embodiments, the stent will be gradually absorbed and/or flushed out of the subject over about 3 weeks-6 months. In operation, the stent can be configured so as to have sufficient thickness and resilience to allow drainage and/or flushing liquids to be directed into the subject therethrough even for a patient undergoing increased internal pressures due to edema during a healing period after a thermal ablation therapy has been applied to a localized region of the prostate. The instant invention can also reduce irritation introduced to the ablated tissue (which can reduce the number of blood clots produced by the subject) over conventional procedures by eliminating the requirement of inserting a physical conventional mechanical type stent.